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Clarify requirements before you design — kept separate from your stage notes.

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Distributed Database System Design

Visual Problem Diagram

Scenario

A network partition splits US-East and EU-West—your "globally consistent" database either rejects writes or forks conflicting rows users never see reconciled. The interview compares Spanner/Paxos, Cassandra tunable consistency, and shard rebalancing honestly.

Design a distributed database that partitions data across nodes, replicates for fault tolerance, and serves queries with defined consistency guarantees. Compare SQL sharding vs leaderless wide-column models for the scenario given.

You should support CRUD, replication, failover, resharding, and consistency levels. Be ready to explain CAP tradeoffs and cross-shard limitations.

Constraints

Functional

SQL/KV CRUD, replication, secondary indexes, transactions per shard, admin resharding

Non-functional

99.99% availability, tunable latency vs consistency, horizontal scale, automatic failover

Scale

Petabytes, millions QPS aggregate, thousands of shards, multi-region

Stages ahead

1Requirement Analysis

2API Design

3High-Level Design

4HLD Extensions

5Trade-offs

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